Field of the Invention
The present invention relates to an optical element molding mold set for molding an optical element, and an optical element manufacturing method for manufacturing the optical element.
Description of the Related Art
Conventionally, when an optical surface and an outer peripheral surface are simultaneously molded by using an upper mold, a lower mold, and an outer peripheral mold such that a lens that does not need to be centered is molded, there is usually a difference in volume between a space between a molding surface of the upper mold and an upper surface of a glass material and a space between a molding surface of the lower mold and a lower surface of the glass material. Therefore, in a cavity that is a space surrounded by the upper mold, the lower mold, and the outer peripheral mold, a difference is generated between the time needed to fill an outer peripheral portion of the molding surface of the upper mold with glass and the time needed to fill an outer peripheral portion of the molding surface of the lower mold with glass.
Due to the difference in time above, when the outer peripheral portions of the molding surface of the upper mold and the molding surface of the lower mold are attempted to be filled with glass, glass flows from an outer peripheral portion of a molding surface of a mold that has been filled earlier into a gap between the mold that has been filled earlier and the outer peripheral mold.
Accordingly, a method has been proposed for performing molding by using upper and lower molds having a difference in temperature such that transformation of a surface on one side of a molding material is delayed (see, for example, Japanese Laid-Open Patent Publication No. 62-128932).